Lake’s water flow issues start in northern Everglades

OKEECHOBEE — You walk into your bathroom and see the bathtub is overflowing. What would you do?

Would you run a hose out the window? Would you gather up pots and pans to store the water? Would you buy a bigger bathtub? Or, would you turn off the tap, and then attempt to unclog the drain?

Think of Lake Okeechobee as a bathtub. During the rainy season, water pours in much too fast from the north – as much as six times faster than it can be released through existing structures. Making matters worse, the flow south is often blocked. The bottom end of the system is dammed by the Tamiami Trail and flow under existing raised portions of the roadway is limited six months of the year to protect the nesting area of an endangered bird.

Lake Okeechobee Inflow

So, the overflow is released east and west.

Freshwater releases from the lake to the Caloosahatchee and St. Lucie rivers are blamed for disrupting salinity levels which make those estuaries – already nutrient rich from runoff into the local basins – ripe for algae blooms. (The lake water is also often unfairly blamed for the nutrient load in those estuaries despite the University of Florida Water Institute studies which found that most of the excess phosphorus and nitrogen comes from direct runoff into the Caloosahatchee River and the St. Lucie canal.)

While some are quick to blame the lake for the algae blooms in the coastal waterways, or demand water managers to “restore the flow” and “send it south,” the answer is not that simple.

If it were possible to restore the natural flow, much of the water that is released east and west to the coastal estuaries during the rainy season would not flow south because it would evaporate into the air or percolate into the earth long before it ever reached the lake.

Consider: The original Everglades starts at Shingle Creek.

Currently, the heaviest flow of water into the lake comes down “the ditch” – what locals call the channelized Kissimmee River. Water managers call it the C-38 canal. The Kissimmee River once meandered for 103 miles, through curves that according to Seminole legend were created by the writhing of a giant snake. During the wet season, the river’s floodplain reached up to 3 miles across. In the 1960s, the Kissimmee River was channelized by cutting and dredging a 30-feet-deep straightaway through the river’s meanders. This flood control project drained land for urban development and agriculture in the northern Everglades.

According to the Florida Oceanographic Society, before the Kissimmee River was channelized, it took six-to-eight months for rainfall from the upper Kissimmee River Basin to sheetflow slowly down to Lake Okeechobee. Now that hydrological trip takes just weeks.

The U.S. Corps of Engineers estimates that a storm that drops one foot of rainfall over the Lake Okeechobee basin could result in a 3-4 foot rise in the lake’s water level in a matter of weeks. In 2017 after Hurricane Irma, as water drained rapidly from the northern watersheds into the Big O, the lake level rose three feet in less than a month.

That’s where the problem starts. The speed at which the Kissimmee River valley drains, thanks to modern flood control, increases the volume of water entering the lake from the north.

The explosion of development at the top of the system in the Orlando area has also increased the volume of water draining into the river. Every rooftop, every driveway, every road, every parking lot, every shopping center, everything that prevents water from soaking into the earth increases the amount and the speed of the runoff.

The faster moving water is also higher in nutrient load. When the water sheetflowed slowly, the plants growing in the marshes that spread out for miles along the river helped to clean it as the marsh plants fed on the nutrients in the water. The marshes were a natural filter system. In addition, the increased human population means an increase in the nutrient load in the runoff.

Another factor to consider: Many longtime residents theorize that the dredging of the channel to straighten the winding river may have dug through natural phosphorus deposits.

According to the research of environmental reporter Twila Valentine, who covered Everglades issues for the Okeechobee News for decades, before the Kissimmee River was channelized, the river contributed about a third of the water and only about 3 to 4 percent of the phosphorus entering Lake Okeechobee each year.

Today, according to South Florida Water Management District data, the river contributes an annual average of about half of the total flow into Lake Okeechobee, and about 36 percent of the phosphorus.

Florida Department of Environmental Protection reports presented at Lake Okeechobee Basin Management (BMAP) meetings have pointed to the connection between the heavier flow to the lake and the increase in phosphorus.

FDEP has set the target for the water in Lake Okeechobee at 40 parts per billion of phosphorus. Based on the most recent five-year average, water flowing into the lake from the Upper Kissimmee Basin averages 78 ppb, water from the Lower Kissimmee Basin averages 201 ppb.

The problem is two fold with both too much phosphorus in the water for the lake to handle as well as too much water, coming in too fast.

The water flowing into the coastal estuaries isn’t coming FROM the lake; it’s coming THROUGH the lake.

Flow south from the lake has also changed.

Before man’s interference in the natural system, water flowed from the lake into the Everglades during the wet season when the lake filled up and spilled out through the marshes south. During the wet season, water from the lake also flowed west through a series of marshes and smaller lakes that fed the Caloosahatchee River.

Thanks to the modern flood control system, water now flows south through canals year round. Flow to the south is limited in part by the capacity of the canals which carry water from Lake Okeechobee south, and by the requirements for flood control in the urban areas beyond East Coast Protection Levy.

In addition, flow south is limited by a man-made dam at the bottom of the system, a roadway that runs coast to coast from Tampa to Miami, bisecting the southern Everglades.

What was once a natural sheet flow to Everglades National Park and Florida Bay is blocked by the Tamiami Trail. The U.S. Army Corps of Engineers has estimated about 11 miles or raised bridging is needed to restore flow south, but only 3.6 miles of bridging has been funded. The Department of the Interior restricts flow under the Trail six months of the year to protect the nesting area of the endangered Cape Sable Sea Sparrow. That means, even when there is capacity to send more water south, and even when water in the Water Conservation Areas meets the 10 ppb phosphorus limit for flow to Everglades National Park, that clean water is sometimes trapped north of the Tamiami Trail.

The Kissimmee River Restoration Project, scheduled for completion in 2020, will restore flow to about 44 miles to the center portion of the original winding river. Per state reports, the restoration project is expected to have some water quality benefits, but it was not designed as a water quality project.

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